Diorama Satchel

 
Because the strap is completely detachable, you can purchase a fun Fendi StrapYou to go with the Diorama Satchel, and keep the fabric strap for when you want to pull off a more utilitarian look.

I understand what you mean about leather bags pairing with leather straps, but fabric straps are quite chic and youthful, and this doesn't just apply to bags. Even prestigious watches are offering fabric NATO straps, which seems outrageous given their high prices and elite image but they are definitely very chic at the moment, and offer a sporty casual vibe to an otherwise dressy watch.

This is the Omega Seamatser for 007 Spectre.

SE_Seamaster300_Spectre_vueC_1600x900.jpg

Great idea about the Fendi strap you option. I have o e but don't use it. Once I get the Diorama Satchel in black I'll definitely use it.